Device and method for clamping and wire-bonding the leads of a lead frame one set at a time

ABSTRACT

A wire-bonding machine includes a heat block for supporting a lead frame during wire-bonding. A clamp mechanism in the machine clamps leads of the lead frame during wire-bonding by fixedly holding sets of the leads against the heat block one set at a time. A wire-bonding tool wire-bonds leads clamped by the clamp mechanism to bond pads on an integrated circuit die. By clamping leads of the lead frame in separate sets, the machine provides improved clamping for lead frames with leads requiring clamping in different planes.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.09/702,568, filed Nov. 2, 2000, pending, which is divisional ofapplication Ser. No. 09/366,817, filed Aug. 4, 1999, now U.S. Pat. No.6,299,049 B1, issued Oct. 9, 2001, which is a continuation ofapplication Ser. No. 08/763,366, filed Dec. 13, 1996, now U.S. Pat. No.6,068,174, issued May 30, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to devices and methods for clampingthe leads of a lead frame while the leads are being wire-bonded to bondpads on an integrated circuit die.

[0004] 2. State of the Art

[0005] Integrated circuit (IC) dice or “chips” are small, generallyrectangular IC devices cut from a semiconductor wafer, such as a siliconwafer, on which multiple ICs have been fabricated. IC dice are typicallypackaged to protect them from corrosion by attaching them to lead framesusing a solder or epoxy, electrically connecting them to leads in thelead frames, and then encapsulating the resulting die and lead frameassemblies in plastic die packages. The leads in the encapsulated leadframes protrude from the die packages and terminate in pins so the diceelectrically connected to the leads can communicate with circuitryexternal to the die packages through the pins.

[0006] IC dice are typically electrically connected to the leads intheir associated lead frames in a process known as “wire-bonding.”During wire-bonding of an IC die to a lead frame, a wire-bonding tool,such as an ultrasonic, thermosonic, or thermo-compression tool, bondslengths of fine wire to bond pads on the die and to bonding sites on theleads in the lead frame in order to connect the bond pads and the leads.This process is well-known, and is described in detail in U.S. Pat. Nos.4,030,657, 4,361,261, 4,527,730, 4,600,138, 4,603,803, 4,765,531,4,778,097, 5,148,959, 5,217,154, 5,251,805, 5,307,978, 5,421,503,5,425,491, 5,445,306, 5,465,899, 5,486,733, 5,513,792, and 5,516,023.

[0007] In order to ensure proper wire-bonding, lead frame leads aretypically clamped during wire-bonding to stabilize them so a solid bondcan be formed between the leads and the fine wire used to wire-bond themto an IC die. Without clamping, the leads can move during wire-bondingand cause unreliable bonds to be formed between the leads and the finewire.

[0008] Conventionally, all the leads in a lead frame are clamped at oncein a single plane during wire-bonding, as shown in U.S. Pat. Nos.3,685,137, 5,035,034, and 5,193,733. By clamping all the leads of a leadframe at once, the conventional clamping method holds to a relativeminimum the time it takes to wire bond an IC die to the lead frame.

[0009] While holding wire-bonding time to a minimum is advantageous, theconventional clamping method can also be problematic with certain leadframes. For example, some lead frames, such as the Leads-Over-Chip leadframe shown in U.S. Pat. No. 4,862,245, have leads which extend closerto the bond pads of IC dice attached to the lead frames than other leadssuch that fine wires bonded between the IC dice and these other leadsmust arch over the leads which are closer to the bond pads on the dice.Since fine wires must arch over the leads closer to the bond pads, thecloser leads cannot be clamped at the same time all the other leads areclamped. Instead, the closer leads conventionally remain unclamped, oronly partially clamped, during wire-bonding, resulting in potentiallyunreliable bonds to those leads.

[0010] Also, because the conventional clamping method clamps all theleads of a lead frame at once in a single plane, it cannot adequatelyclamp leads of a lead frame which must be clamped in different planes.For example, as shown in U.S. Pat. No. 4,943,843, some Tape-Under-Framelead frames have leads which extend underneath an IC die and thenproject beyond the footprint of the die so they may be wire-bonded tobond pads on the die. These leads are typically left unclamped duringwire-bonding, because they are not clampable in accordance with theconventional clamping method in the same plane as the remainder of theleads. As a result, these leads have potentially unreliable wire bonds.In a similar fashion, the conventional clamping method cannot adequatelyclamp multi-layer lead frames, such as that shown in U.S. Pat. No.5,291,061.

[0011] Wire-bonding clamps, such as that shown in U.S. Pat. No.4,821,945, have been developed to alleviate some of the problems of theconventional clamping method by clamping leads individually. However,these clamps can dramatically increase the time it takes to wire-bond anIC die, because the clamp must be sequentially indexed to eachindividual lead.

[0012] Therefore, there is a need in the art for a device and method forclamping lead frame leads during wire-bonding that can clamp leads indifferent planes without significantly increasing the time it takes towire-bond an IC die.

BRIEF SUMMARY OF THE INVENTION

[0013] An inventive wire-bonding apparatus includes a base forsupporting a lead frame during wire-bonding. A clamp mechanism in theapparatus fixedly holds sets of leads of the lead frame against the baseone set at a time, with each set including fewer than all the leads andat least one set including more than one of the leads. Also, awire-bonding tool wire-bonds leads fixedly held against the base by theclamp mechanism to bond pads on an integrated circuit (IC) die. As aresult, leads in different planes can be effectively clamped andwire-bonded in separate sets, yet the leads within each set are allclamped at the same time, so the wire-bonding time for an IC die is keptto a minimum.

[0014] Further embodiments include a clamping apparatus which includesthe base and clamp mechanism described above and the clamp mechanismdescribed above by itself.

[0015] In an additional embodiment, a bonding machine for wire bondingleads of lead frames in a lead frame strip to bond pads on IC diceattached to the lead frames includes a heat block with a contact areafor heating the dice and the lead frames. An indexing mechanism indexesthe lead frame strip through the bonding machine so each lead frame inthe strip is sequentially indexed to the heat block's contact area. Aclamp mechanism fixedly holds sets of the leads of each lead frameindexed to the heat block's contact area against the heat block one setat a time, and a wire-bonding tool wire-bonds the leads in each set heldagainst the heat block to bond pads on the IC die attached to the leadframe of the held leads.

[0016] In another embodiment, a bonding machine similar to thatdescribed above simultaneously clamps and wire-bonds sequential leadframes in a lead frame strip at multiple contact areas on a heat block.

[0017] In a still further embodiment, a bonding machine for wire bondingleads of a Tape-Under-Frame (TUF) lead frame to bond pads on afront-side surface of an IC die attached to the TUF lead frame includesa heat block for supporting and heating the die and the TUF lead frame.A clamp mechanism fixedly holds a first set of leads of the TUF leadframe, which extends in a plane of a backside surface of the IC die tosupport the die, and a second set of leads of the TUF lead frame, whichextends in the plane of the front-side surface of the IC die, againstthe heat block one set at a time. Also, a wire-bonding tool wire bondsthe leads in each set of leads fixedly held against the heat block tobond pads on the IC die.

[0018] In still another embodiment, a bonding machine for wire bondingleads of a partial Leads-Over-Chip (LOC) lead frame to bond pads on anIC die includes a heat block for supporting and heating the die and thepartial LOC lead frame. A clamp mechanism fixedly holds LOC leads of thepartial LOC lead frame against the die, and other leads which terminateproximate the perimeter of the IC die against the heat block, atdifferent times. Also, a wire bonding tool wire bonds the fixedly-heldleads to bond pads on the IC die.

[0019] In yet another embodiment, a bonding machine for wire bonding busbar and non-bus bar LOC leads of an LOC lead frame to bond pads on an ICdie attached to and supported by the LOC leads includes a heat block forsupporting and heating the die and the LOC lead frame. A clamp mechanismfixedly holds the bus bar and non-bus bar LOC leads against the die atdifferent times, and a wire-bonding tool wire bonds the fixedly-held LOCleads to bond pads on the IC die.

[0020] In another additional embodiment, a bonding machine for wirebonding leads of a lead frame to bond pads on an IC die attached to thelead frame includes a heat block for supporting and heating the die andthe lead frame. A clamp mechanism fixedly holds a first set of the leadsof the lead frame, which extend toward the die and terminate proximatethe die's perimeter in a first plane, and a second set of the leads ofthe lead frame, which extend toward the die and terminate proximate thedie's perimeter in a second plane different than the first, against theheat block at different times. Also, a wire-bonding tool wire bonds thefixedly-held leads to bond pads on the IC die.

[0021] In a further embodiment, a method for clamping leads of a leadframe includes clamping a set of the leads at a time with each setincluding fewer than all the leads and at least one set including morethan one of the leads.

[0022] In a still further embodiment, a method for wire bonding leads oflead frames in a lead frame strip to bond pads on IC dice attached tothe lead frames includes: sequentially indexing each lead frame in thestrip to a clamping position; clamping the leads of each lead frameindexed to the clamping position one set at a time with each setincluding fewer than all the leads of the lead frame and at least oneset including more than one of the leads; and wire bonding each set ofclamped leads to bond pads on the IC die attached to the lead frame ofthe clamped leads.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0023]FIGS. 1A and 1B are isometric views of a lead frame clamped andwire-bonded to an integrated circuit (IC) die in accordance with oneembodiment of the present invention;

[0024]FIGS. 2A and 2B are isometric views of a Leads-Over-Chip (LOC)lead frame clamped and wire-bonded to an IC die in accordance withanother embodiment of the present invention;

[0025]FIGS. 3A and 3B are isometric views of a partial LOC lead frameclamped and wire-bonded to an IC die in accordance with a furtherembodiment of the present invention;

[0026]FIGS. 4A and 4B are isometric views of a Tape-Under-Frame (TUF)lead frame clamped and wire-bonded to an IC die in accordance with anadditional embodiment of the present invention;

[0027]FIGS. 5A and 5B are isometric views of a single-piece, multi-levellead frame clamped and wire-bonded to an IC die in accordance with yetanother embodiment of the present invention;

[0028]FIGS. 6A and 6B are isometric views of a two-piece, multi-levellead frame clamped and wire-bonded to an IC die in accordance with astill further embodiment of the present invention; and

[0029]FIGS. 7A and 7B are isometric views of wire-bonding machines whichincorporate the respective clamping embodiments of FIGS. 2A,2B and5A,5B.

DETAILED DESCRIPTION OF THE INVENTION

[0030] As shown in FIG. 1A, a portion 10 of a clamp mechanism inaccordance with the present invention includes a plurality of clampmembers 12 moving together as directed by an actuating mechanism (notshown) in a wire-bonding machine (not shown) to fixedly hold a first setof leads 14 of a lead frame 16 against a heat block or other base (notshown) beneath the lead frame 16. Once the leads 14 are fixedly held(i.e., clamped) by the clamp members 12, they may be wire-bonded using awire bond tool (not shown) to selected bond pads on a front-side surfaceof an integrated circuit (IC) die 20 attached to the lead frame 16.

[0031] As shown in FIG. 1B, the leads 14 of the lead frame 16 have beenwire-bonded to bond pads on the IC die 20 while being clamped asdescribed above and the lead frame 16 has been indexed to a new clampinglocation with respect to the clamp mechanism of FIG. 1A. Another portion22 of the clamp mechanism includes a clamp block 24 moving as directedby the actuating mechanism (not shown) of FIG. 1A to fixedly hold asecond set of leads 26 of the lead frame 16 against the heat block orother base (not shown) beneath the lead frame 16. Once the leads 26 arefixedly held by the clamp block 24, they may be wire-bonded through abonding aperture 28 in the clamp block 24 to bond pads on the front-sidesurface of the IC die 20 using a wire bond tool (not shown).

[0032] By clamping the leads 14 and 26 of the lead frame 16 in separatesets in accordance with the present invention, the leads 14 interposedbetween the IC die 20 and the leads 26 can be clamped while they arewire-bonded. This is in contrast to the conventional clamping methoddescribed above which would only clamp the leads of the lead frame 16once, and thus would not clamp the leads 14, since to do so while alsoclamping the leads 26 would interfere with the wire-bonding of the leads26.

[0033] It will be understood by those having skill in the field of thisinvention that the clamp mechanism of FIGS. 1A and 1B may take a varietyof forms, and that the present invention includes within its scope allclamp mechanisms capable of clamping the leads of a lead frame in sets,one set at a time. It will also be understood that the clamp mechanismmay comprise a variety of clamp members, including, for example, one ormore clamp blocks, as shown in FIG. 1B, or one or more clamp fingers, asdescribed below with respect to FIG. 3B.

[0034] It will further be understood that the clamp mechanism mayinclude one or more clamp members for clamping each set of leads in alead frame, and that each of the plurality of clamp members mayindividually clamp one or several leads in the set. In addition, it willbe understood that, although the present invention will be describedwith respect to a clamp mechanism clamping the leads of a lead frame intwo sets in a particular order, the present invention includes withinits scope clamp mechanisms which clamp the leads of a lead frame in morethan two sets in any order. Further, it will be understood that thepresent invention includes within its scope: clamp mechanisms that clampall the sets of leads of a lead frame at different times but at the sameclamping location; clamp mechanisms, such as that described with respectto FIGS. 1A and 1B, that clamp the sets of leads of a lead frame atdifferent times and at different clamping locations; and any combinationthereof. It will also be understood that a wide variety of lead frames,including, for example, Leads-Over-Chip (LOC) lead frames andTape-Under-Frame (TUF) lead frames, and any wire-bondable IC die, willwork in conjunction with the present invention.

[0035] As shown in FIG. 2A, a portion of a clamp mechanism in accordancewith another embodiment of the present invention includes a clamp block30 moving as directed by an actuating mechanism (not shown) in awire-bonding machine (not shown) to fixedly hold bus bar LOC leads 32 ofan LOC lead frame 34 against an IC die 36 attached to the LOC lead frame34 and supported by a heat block or other base (not shown). Once the busbar LOC leads 32 are fixedly held (i.e., clamped) by the clamp block 30,they may be wire-bonded using a wire bond tool (not shown) to selectedbond pads on a front-side surface of the IC die 36. Afterward, the clampblock 30 is moved away from the LOC lead frame 34 by the actuatingmechanism (not shown).

[0036] As shown in FIG. 2B, the bus bar LOC leads 32 of the LOC leadframe 34 have been wire-bonded to bond pads on the IC die 36 while beingclamped as described above and the clamp block 30 (FIG. 2A) has beenmoved away from the LOC lead frame 34. Another portion of the clampmechanism of FIG. 2A includes a clamp block 38 moving as directed by theactuating mechanism (not shown) of FIG. 2A to fixedly hold non-bus barLOC leads 40 of the LOC lead frame 34 against the IC die 36. Once theleads 40 are fixedly held by the clamp block 38, they may be wire-bondedthrough a bonding aperture 42 in the clamp block 38 to bond pads on thefront-side surface of the IC die 36 using the wire bond tool (not shown)of FIG. 2A.

[0037] By clamping the bus bar LOC leads 32 and non-bus bar LOC leads 40of the LOC lead frame 16 at different times in accordance with thepresent invention, the bus bar LOC leads 32 interposed between bond padson the front-side surface of the IC die 36 and the non-bus bar LOC leads40 can be fully clamped while they are wire-bonded. This is in contrastto the conventional clamping method described above which would onlyclamp the LOC leads 32 and 40 of the LOC lead frame 34 once, and thuswould not fully clamp the bus bar LOC leads 32, since to do so whilealso clamping the non-bus bar LOC leads 40 would interfere with thewire-bonding of the non-bus bar LOC leads 40.

[0038] It will be understood that the clamp mechanism of FIGS. 2A and 2Bmay take a variety of forms, and that the present invention includeswithin its scope all clamp mechanisms capable of clamping the LOC leadsof an LOC lead frame in sets, one set at a time and in any order. Itwill also be understood that the clamp mechanism may comprise a varietyof clamp members, including, for example, one or more clamp blocks, asshown in FIGS. 2A and 2B, or one or more clamp fingers, as describedbelow with respect to FIG. 3B. It will further be understood that theclamp mechanism may include one or more clamp members for clamping eachset of LOC leads in an LOC lead frame, and that each of the clampmembers may individually clamp one or several LOC leads in the set.Further, it will be understood that the present invention includeswithin its scope: clamp mechanisms that clamp all the sets of LOC leadsof an LOC lead frame at different times but at the same clampinglocation, as shown in FIGS. 2A and 2B; clamp mechanisms, such as thatshown in FIGS. 1A and 1B, that clamp the sets of leads of a lead frameat different times and at different clamping locations; and anycombination thereof.

[0039] As shown in FIG. 3A, a portion of a clamp mechanism in accordancewith a further embodiment of the present invention includes a clampblock 50 moving as directed by an actuating mechanism (not shown) in awire-bonding machine (not shown) to fixedly hold LOC leads 52 of apartial LOC lead frame 54 against an IC die 56 attached to the partialLOC lead frame 54 and supported by a heat block or other base (notshown). Once the LOC leads 52 are fixedly held (i.e., clamped) by theclamp block 50, they may be wire-bonded through a bonding aperture 58 inthe clamp block 50 to selected bond pads on a front-side surface of theIC die 56 using a wire bond tool (not shown).

[0040] As shown in FIG. 3B, the LOC leads 52 of the partial LOC leadframe 54 have been wire-bonded to bond pads on the IC die 56 while beingclamped as described above and the LOC lead frame 54 has been indexed toa new clamping location with respect to the clamp mechanism of FIG. 3A.Another portion 60 of the clamp mechanism of FIG. 3A includes clampfingers 62 moving together as directed by the actuating mechanism (notshown) of FIG. 3A to fixedly hold non-LOC leads 64 of the partial LOClead frame 54 against the heat block or other base (not shown) in adifferent plane than the plane of the front-side surface of the IC die56. Once the non-LOC leads 64 are fixedly held by the clamp fingers 62,they may be wire-bonded using a wire bond tool (not shown) to bond padson the front-side surface of the IC die 56.

[0041] By clamping the LOC leads 52 and non-LOC leads 64 of the partialLOC lead frame 54 at different times in accordance with the presentinvention, the LOC leads 52 and the non-LOC leads 64 can be fullyclamped while they are wire-bonded despite being clamped in differentplanes. This is in contrast to the conventional clamping methoddescribed above which would clamp the LOC leads 52 and the non-LOC leads64 at the same time, and thus may fail to fully clamp some of the leads52 and 64.

[0042] It will be understood that the clamp mechanism of FIGS. 3A and 3Bmay take a variety of forms, and that the present invention includeswithin its scope all clamp mechanisms capable of clamping the leads of apartial LOC lead frame in sets, one set at a time and in any order. Itwill also be understood that the clamp mechanism may comprise a varietyof clamp members, including, for example, one or more clamp blocks, asshown in FIG. 3A, or one or more clamp fingers, as shown in FIG. 3B. Itwill further be understood that the clamp mechanism may include one ormore clamp members for clamping each set of leads in a partial LOC leadframe, and that each of the plurality of clamp members may individuallyclamp one or several leads in the set. Further, it will be understoodthat the present invention includes within its scope: clamp mechanismsthat clamp all the sets of leads of a partial LOC lead frame atdifferent times but at the same clamping location; clamp mechanisms,such as that shown in FIGS. 3A and 3B, that clamp the sets of leads of alead frame at different times and at different clamping locations; andany combination thereof.

[0043] As shown in FIG. 4A, a portion of a clamp mechanism in accordancewith an additional embodiment of the present invention includes a clampblock 70 moving as directed by an actuating mechanism (not shown) in awire-bonding machine (not shown) to fixedly hold Tape-Under-Frame (TUF)leads 72 of a TUF lead frame 74 against a heat block or other base (notshown) by pressing against the front-side surface of an IC die 76attached to the TUF lead frame 74. Once the TUF leads 72 are fixedlyheld (i.e., clamped) by the clamp block 70, they may be wire-bonded toselected bond pads on the front-side surface of the IC die 76 using awire bond tool (not shown).

[0044] As shown in FIG. 4B, the TUF leads 72 of the TUF lead frame 74have been wire-bonded to bond pads on the IC die 76 while being clampedas described above and the TUF lead frame 74 has been indexed to a newclamping location with respect to the clamp mechanism of FIG. 4A.Another portion 78 of the clamp mechanism of FIG. 4A includes clampblocks 80 moving together as directed by the actuating mechanism (notshown) of FIG. 4A to fixedly hold non-TUF leads 82 of the TUF lead frame74 against the heat block or other base (not shown). Once the non-TUFleads 82 are fixedly held by the clamp blocks 80, they may bewire-bonded using a wire bond tool (not shown) to bond pads on thefront-side surface of the IC die 76.

[0045] By clamping the TUF leads 72 and non-TUF leads 82 of the TUF leadframe 74 at different times in accordance with the present invention,both sets of leads 72 and 82 can be fully clamped while they arewire-bonded despite being clamped in different planes. This is incontrast to the conventional clamping method described above which wouldclamp the TUF leads 72 and the non-TUF leads 82 at the same time, andthus may fail to fully clamp some of the leads 72 and 82.

[0046] It will be understood that the clamp mechanism of FIGS. 4A and 4Bmay take a variety of forms, and that the present invention includeswithin its scope all clamp mechanisms capable of clamping the leads of aTUF lead frame in sets, one set at a time and in any order. It will alsobe understood that the clamp mechanism may comprise a variety of clampmembers, including, for example, one or more clamp blocks, as shown inFIGS. 4A and 4B, or one or more clamp fingers, as shown in FIG. 3B. Itwill further be understood that the clamp mechanism may include one ormore clamp members for clamping each set of leads in a TUF lead frame,and that each of the plurality of clamp members may individually clampone or several leads in the set. Further, it will be understood that thepresent invention includes within its scope: clamp mechanisms that clampall the sets of leads of a TUF lead frame at different times but at thesame clamping location; clamp mechanisms, such as that shown in FIGS. 4Aand 4B, that clamp the sets of leads of a lead frame at different timesand at different clamping locations; and any combination thereof.

[0047] As shown in FIG. 5A, a portion of a clamp mechanism in accordancewith yet another embodiment of the present invention includes a clampblock 90 moving as directed by an actuating mechanism (not shown) in awire-bonding machine (not shown) to fixedly hold a first set of leads 92of a multi-level lead frame 94 against a heat block or other base (notshown) beneath the multi-level lead frame 94. Once the leads 92 arefixedly held (i.e., clamped) by the clamp block 90, they may bewire-bonded with a wire bond tool (not shown) inserted through a bondingaperture 98 in the clamp block 90 to selected bond pads on thefront-side surface of an IC die 96 attached at its backside surface tothe multi-level lead frame 94.

[0048] As shown in FIG. 5B, the leads 92 of the multi-level lead frame94 have been wire-bonded to bond pads on the IC die 96 while beingclamped as described above and the multi-level lead frame 94 has beenindexed to a new clamping location with respect to the clamp mechanismof FIG. 5A. Another portion of the clamp mechanism of FIG. 5A includes aclamp block 100 moving as directed by the actuating mechanism (notshown) of FIG. 5A to fixedly hold a second set of leads 102 of themulti-level lead frame 94 against the heat block or other base (notshown). Once the leads 102 are fixedly held by the clamp block 100, theymay be wire-bonded with a wire bond tool (not shown) inserted through abonding aperture 104 in the clamp block 100 to bond pads on thefront-side surface of the IC die 96.

[0049] By clamping the first set of leads 92 and the second set of leads102 of the multi-level lead frame 94 at different times in accordancewith the present invention, both sets of leads 92 and 102 can be fullyclamped while they are wire-bonded despite being clamped in differentplanes. This is in contrast to the conventional clamping methoddescribed above which would clamp the first set of leads 92 and thesecond set of leads 102 at the same time, and thus may fail to fullyclamp some of the leads 92 and 102.

[0050] It will be understood that the clamp mechanism of FIGS. 5A and 5Bmay take a variety of forms, and that the present invention includeswithin its scope all clamp mechanisms capable of clamping the leads of amulti-level lead frame in sets, one set at a time and in any order. Itwill also be understood that the clamp mechanism may comprise a varietyof clamp members, including, for example, one or more clamp blocks, asshown in FIGS. 5A and 5B, or one or more clamp fingers, as shown in FIG.3B. It will further be understood that the clamp mechanism may includeone or more clamp members for clamping each set of leads in a multilevellead frame, and that each of the clamp members may individually clampone or several leads in the set. Further, it will be understood that thepresent invention includes within its scope: clamp mechanisms that clampall the sets of leads of a multi-level lead frame at different times butat the same clamping location; clamp mechanisms, such as that shown inFIGS. 5A and 5B, that clamp the sets of leads of a lead frame atdifferent times and at different clamping locations; and any combinationthereof.

[0051] As shown in FIG. 6A, a portion 110 of a clamp mechanism inaccordance with a still further embodiment of the present inventionincludes clamp blocks 112 moving as directed by an actuating mechanism(not shown) in a wire-bonding machine (not shown) to fixedly hold afirst set of leads 114 of a multi-level, two-piece lead frame 116against a heat block or other base (not shown) beneath the lead frame116. Once the leads 114 are fixedly held (i.e., clamped) by the clampblocks 112, they may be wire-bonded with a wire bond tool (not shown) toselected bond pads on the front-side surface of an IC die 118 attachedat its backside surface to the lead frame 116.

[0052] As shown in FIG. 6B, the leads 114 of the lead frame 116 havebeen wire-bonded to bond pads on the IC die 118 while being clamped asdescribed above and the lead frame 116 has been indexed to a newclamping location with respect to the clamp mechanism of FIG. 6A.Another portion 120 of the clamp mechanism of FIG. 6A includes clampblocks 122 moving as directed by the actuating mechanism (not shown) ofFIG. 6A to fixedly hold a second set of leads 124 of the lead frame 116against the heat block or other base (not shown). Once the leads 124 arefixedly held by the clamp blocks 122, they may be wire-bonded with awire bond tool (not shown) to bond pads on the front-side surface of theIC die 118.

[0053] By clamping the first set of leads 114 and the second set ofleads 124 of the lead frame 116 at different times in accordance withthe present invention, both sets of leads 114 and 124 can be fullyclamped while they are wire-bonded despite being clamped in differentplanes. This is in contrast to the conventional clamping methoddescribed above which would clamp the first set of leads 114 and thesecond set of leads 124 at the same time, and thus may fail to fullyclamp some of the leads 114 and 124.

[0054] It will be understood that the clamp mechanism of FIGS. 6A and 6Bmay take a variety of forms, and that the present invention includeswithin its scope all clamp mechanisms capable of clamping the leads of amulti-level, two-piece lead frame in sets, one set at a time and in anyorder. It will also be understood that the clamp mechanism may comprisea variety of clamp members, including, for example, one or more clampblocks, as shown in FIGS. 6A and 6B, or one or more clamp fingers, asshown in FIG. 3B. It will further be understood that the clamp mechanismmay include one or more clamp members for clamping each set of leads ina multi-level, two-piece lead frame, and that each of the clamp membersmay individually clamp one or several leads in the set. Further, it willbe understood that the present invention includes within its scope:clamp mechanisms that clamp all the sets of leads of a multi-level leadframe at different times but at the same clamping location; clampmechanisms, such as that shown in FIGS. 6A and 6B, that clamp the setsof leads of a lead frame at different times and at different clampinglocations; and any combination thereof.

[0055] As shown in FIG. 7A, the clamp blocks 30 and 38 (not shown inFIG. 7A) of FIGS. 2A and 2B may be incorporated into a clamp mechanism130 in a wire-bonding machine 132. An indexing mechanism 134 in themachine 132 sequentially indexes LOC lead frames in a lead frame strip136 to a contact area on a heat block 138. While positioned proximatethe contact area, each LOC lead frame in the lead frame strip 136 isclamped using the clamp blocks 30 and 38 (not shown in FIG. 7A) of FIGS.2A and 2B as described above and is wire bonded as described above usinga wire bonding tool 140 inserted through a bonding window 142 in theclamp mechanism 130.

[0056] Also, a wire bond test device 144, such as a pull test device ora shear test device, inserted through the bonding window 142 during wirebonding tests completed wire bonds once the wire bonding tool 140 moveson to other bonding sites.

[0057] It will be understood by those having skill in the field of thisinvention that a wide variety of indexing mechanisms and heat blockswill work for purposes of this invention. It will also be understoodthat the bonding machine 132 of FIG. 7A will work with any clampmechanism capable of clamping the leads of a lead frame in sets, one setat a time. Further, it will be understood that the wire bonding tool 140may comprise one or more bonding tools, including, for example,ultrasonic, thermosonic, and thermo-compression bonding tools.

[0058] As shown in FIG. 7B, the clamp blocks 90 and 100 (not shown inFIG. 7B) of FIGS. 5A and 5B may be incorporated into a clamp mechanism150 in a wire-bonding machine 152. An indexing mechanism 154 in themachine 152 indexes lead frames in a lead frame strip 156 in turn toeach of a pair of contact areas on a heat block 158. While positionedproximate the contact areas, each lead frame in the lead frame strip 156is clamped using the clamp blocks 90 and 100 (not shown in FIG. 7B) ofFIGS. 5A and 5B as described above and is wire bonded as described aboveusing a wire bonding tool system 160 including a pair of wire-bondingtools 162 inserted through bonding windows 164 in the clamp mechanism150.

[0059] Also, a wire bond test device system 166 including wire bond testdevices 168, such as pull test devices or shear test devices, insertedthrough the bonding windows 164 during wire bonding tests completed wirebonds once the wire bonding tools 162 move on to other bonding sites.

[0060] It will be understood by those having skill in the field of thisinvention that a wide variety of indexing mechanisms and heat blockswill work for purposes of this invention. It will also be understoodthat the bonding machine 152 of FIG. 7B will work with any clampmechanism capable of clamping the leads of a lead frame in sets, one setat a time. Further, it will be understood that the wire bonding tools162 may comprise any bonding tools, including, for example, ultrasonic,thermosonic, and thermo-compression bonding tools.

[0061] Although the present invention has been described with referenceto particular embodiments, the invention is not limited to theseembodiments. Rather, the invention is limited only by the appendedclaims, which include within their scope all equivalent devices ormethods that operate according to the principles of the invention asdescribed.

What is claimed is:
 1. An apparatus for connecting leads of a lead frameto bond pads on an integrated circuit die, the apparatus comprising: abase for supporting the lead frame; a clamp mechanism holding aplurality of sets of the leads against the base one set at a time, eachset of said plurality of sets including fewer than all of the leads ofsaid lead frame, at least one set of the said plurality of setsincluding more than one of the leads; at least one of a wire-bond pulltest device and a wire-bond shear test device for testing wire bonds ofheld leads; and a bonding tool for connecting leads held by the clampmechanism to the bond pads on the integrated circuit die.
 2. Theapparatus of claim 1, wherein the base comprises a heat block forsupporting and heating the lead frame.
 3. The apparatus of claim 1,wherein the clamp mechanism comprises one or more clamp members holdinga set of the leads at a time against the base.
 4. The apparatus of claim3, wherein each clamp member is constructed to hold at least one of theplurality of sets of leads against the base.
 5. The apparatus of claim3, wherein at least two of the clamp members are constructed tocooperate holding at least one set of leads of the plurality of sets ofleads against the base.
 6. The apparatus of claim 3, wherein each clampmember is constructed to hold only one of the leads of a set of leads ofsaid plurality of sets of leads against the base.
 7. The apparatus ofclaim 3, wherein each clamp member is selected from a group comprising aclamp block and a clamp finger.
 8. The apparatus of claim 1, wherein thebonding tool is selected from a group comprising an ultrasonic bondingtool, a thermosonic bonding tool, and a thermo-compression bonding tool.9. A bonding machine for bonding leads of lead frames in a lead framestrip to bond pads on integrated circuit dice attached to the leadframes, the bonding machine comprising: a heat block having a contactarea thereon for heating the dice and the lead frames; an indexingmechanism for indexing the lead frame strip through the bonding machineso each lead frame in the strip is sequentially indexed to a positionproximate the contact area on the heat block; a clamp mechanism holdingsets of the leads of each lead frame indexed to the heat block contactarea against the heat block one set at a time, each set of the sets ofleads including fewer than all the leads, at least one set of the setsof leads including more than one of the leads; at least one of awire-bond pull test device and a wire-bond shear test device for testingwire bonds of leads of each lead frame indexed to the heat block contactarea while the clamp mechanism holds other leads of the lead frameagainst the heat block; and a bonding tool for bonding the leads in eachset of the sets of leads held against the heat block by the clampmechanism to bond pads on the integrated circuit die attached to thelead frame of the held leads.
 10. A bonding machine for wire bondingleads of lead frames in a lead frame strip to bond pads on integratedcircuit dice attached to the lead frames, the bonding machinecomprising: a heat block having a plurality of contact areas thereon forheating the dice and the lead frames; an indexing mechanism for indexingthe lead frame strip through the bonding machine, each lead frame in thestrip being indexed, in turn, to positions proximate each of theplurality of contact areas on the heat block; a clamp mechanism holdingthe leads of each lead frame indexed to each of said plurality of heatblock contact areas against the heat block, the clamp mechanismconstructed to hold a plurality of sets of the leads of each such leadframe one set of leads at a time, each set of the leads of each suchlead frame including fewer than all the leads of the lead frame, atleast one set of the sets of leads of each such lead frame includingmore than one of the leads of the lead frame; at least one of awire-bond pull test system and a wire-bond shear test system for testingwire bonds of leads of each of the lead frames indexed to the pluralityof heat block contact areas while the clamp mechanism holds other leadsof the lead frames against the heat block; and a bonding tool system forbonding the leads held against the heat block by the clamp mechanism tobond pads on the integrated circuit dice attached to the lead frames ofthe held leads.
 11. The bonding machine of claim 10, wherein the clampmechanism is constructed to simultaneously hold a set of the leads ofthe lead frame indexed to each of the plurality of heat block contactareas against the heat block.
 12. The bonding machine of claim 10,wherein the wire-bond pull test system comprises a plurality of testdevices, each selected from a group comprising a wire-bond pull testdevice and a wire-bond shear test device.
 13. The bonding machine ofclaim 10, wherein the wire-bonding tool system comprises more than onewire-bond tool.
 14. A bonding machine for wire bonding leads of a leadframe to bond pads on an integrated circuit die attached to the leadframe, a first set of the leads extending toward the integrated circuitdie and terminating proximate the perimeter thereof in a first planeparallel to a front-side surface of the integrated circuit die, a secondset of the leads extending toward the integrated circuit die andterminating proximate the perimeter thereof in a second plane differentthan the first and parallel to the front-side surface of the integratedcircuit die, the bonding machine comprising: a heat block for supportingand heating the integrated circuit die and the lead frame; a clampmechanism holding the first and second sets of leads against the heatblock at different times; at least one of a wire-bond pull test systemand a wire-bond shear test system for testing wire bonds of leads ofeach of the leads of a lead frame; and a bonding tool for bonding thefixedly-held leads to bond pads on the integrated circuit die.
 15. Thebonding machine of claim 14, wherein the lead frame comprises atwo-piece lead frame.
 16. The bonding machine of claim 14, wherein thelead frame comprises a single piece lead frame.
 17. Apparatus forconnecting leads of a lead frame to bond pads on an integrated circuitdie, the apparatus comprising: a base for supporting a portion of thelead frame; a clamp mechanism holding a plurality of sets of the leadsagainst the base one set at a time, each set of said plurality of setsincluding fewer than all of the leads of said lead frame, at least oneset of the said plurality of sets including more than one of the leads;at least one of a wire-bond pull test device and a wire-bond shear testdevice for testing wire bonds of held leads; and a bonding tool forconnecting leads held by the clamp mechanism to the bond pads on theintegrated circuit die.
 18. The apparatus of claim 17, wherein the basecomprises a heat block for supporting and heating am portion of the leadframe.
 19. The apparatus of claim 17, wherein the clamp mechanismcomprises one or more clamp members holding at least one lead of a setof the leads at a time against the base.
 20. The apparatus of claim 19,wherein each clamp member is constructed to hold at least one set ofleads of the plurality of sets of leads against the base.
 21. Theapparatus of claim 20, wherein at least two of the clamp members areconstructed to cooperate holding at least one set of leads of theplurality of sets of leads against the base.
 22. The apparatus of claim21, wherein each clamp member is constructed to hold only one lead of aset of leads of said plurality of sets of leads against the base. 23.The apparatus of claim 21, wherein each clamp member is selected from agroup comprising a clamp block and a clamp finger.
 24. The apparatus ofclaim 17, wherein the bonding tool is selected from a group comprisingan ultrasonic bonding tool, a thermosonic bonding tool, and athermo-compression bonding tool.
 25. A wire bonding machine forconnecting the leads of lead frames in a lead frame strip to bond padson integrated circuit dice attached to the lead frames using wire bonds,the bonding machine comprising: a heat block having a contact areathereon for heating the integrated circuit dice and the lead frames; anindexing mechanism for indexing the lead frame strip through the bondingmachine so each lead frame in the strip is sequentially indexed to aposition proximate the contact area on the heat block; a clamp mechanismholding at least a portion of one set of leads of the leads of each leadframe indexed to the heat block contact area against the heat block oneset at a time, each set of the sets of leads including fewer than allthe leads, at least one set of the sets of leads including more than oneof the leads; at least one of a wire-bond pull test device and awire-bond shear test device for testing wire bonds of leads of each leadframe indexed to the heat block contact area while the clamp mechanismholds other leads of the lead frame against the heat block; and abonding tool for bonding the leads in each set of the sets of leads heldagainst the heat block by the clamp mechanism to bond pads on theintegrated circuit die attached to the lead frame of the held leadsusing wire bonds.
 26. A wire bonding machine for connecting leads oflead frames in a lead frame strip to bond pads on integrated circuitdice attached to the lead frames, said wire bonding machine comprising:a heat block having a plurality of contact areas thereon for heating thedice and the lead frames; an indexing mechanism for indexing the leadframe strip through the wire bonding machine, each lead frame in thestrip being indexed, in turn, to positions proximate each of theplurality of contact areas on the heat block; a clamp mechanism holdingthe leads of each lead frame indexed to each of said plurality of heatblock contact areas against the heat block, the clamp mechanismconstructed to hold a plurality of sets of the leads of each such leadframe one set of leads at a time, each set of the leads of each suchlead frame including fewer than all the leads of the lead frame, atleast one set of the sets of leads of each such lead frame includingmore than one of the leads of the lead frame; at least one of awire-bond pull test system and a wire-bond shear test system for testingwire bonds of leads of each of the lead frames indexed to the pluralityof heat block contact areas while the clamp mechanism holds other leadsof the lead frames against the heat block; and a wire bonding toolsystem for bonding the leads held against the heat block by the clampmechanism to bond pads on the integrated circuit dice attached to thelead frames of the held leads.
 27. The wire bonding machine of claim 26,wherein the clamp mechanism is constructed to simultaneously hold a setof the leads of the lead frame indexed to each of the plurality of heatblock contact areas against the heat block.
 28. The wire bonding machineof claim 26, wherein the wire-bond pull test system comprises aplurality of test devices, each selected from a group comprising awire-bond pull test device and a wire-bond shear test device.
 29. Thewire bonding machine of claim 26, wherein the wire-bonding tool systemcomprises more than one wire-bond tool.